Methods and apparatus for clarification of pyrolysis oils

ABSTRACT

The present invention provides a method and apparatus for processing to improve the properties of pyrolysis oil and, as a result, the commercial value of the same. The net result is creation of an oil with a much lighter color in lieu of the black color, reducing or elimination the undesired sulfury/amine aroma and reducing the amount of PAH which is believed to be a carcinogen.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/717,264 filed Sep. 27, 2017 entitled “Methods and Apparatusfor Clarification of Pyrolysis Oils”, the disclosure of which isexpressly incorporated herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to methods and apparatus for convertingthe black color of pyrolysis oil derived from thermal treatment ofvehicle tires or other waste materials to a lighter more yellow color.It also relates to methods and apparatus for removing polar compoundsfrom pyrolysis oil and reducing the polyaromatic hydrocarbons (PAH)levels in the pyrolysis oils.

2. Description of the Prior Art

It has been known to employ methods of pyrolysis of hydrocarbonmaterials such as waste vehicle tires to produce useful byproducts. Thisnot only minimizes the problem of huge accumulations of discarded tires,but produces economically worthwhile products. See U.S. Pat. No.6,833,485, for example. The pyrolysis process may produce a carbonproduct, a liquid hydrocarbon product and a combustible gas.

U.S. Pat. No. 6,835,861 discloses a low energy method of pyrolysis ofhydrocarbon materials which employs a clay and metal catalyst. Itproduces a solid carbonaceous material, an oil and combustible gasproducts. The carbon black produced by the recited method was said tocontain no detectable PAHs. The carbon char is said to be usable as asource of fuel. High purity carbon blacks were said to be usable fortoner and electrical sensors. Liquid oil and gas produced by the methodare said to be easily separable from the system.

U.S. Pat. Nos. 8,263,038 and 8,512,643 recite a method of devolatilizingrecycled carbon black obtained from the pyrolysis of tires bydeagglomerating the recycled carbon black to reduce the black particlesize and impinging a countercurrent air current on the black particlesto increase the processing temperature and enhance release of volatiles.

Pyrolysis oil produced by heating rubber, such as tire rubber in theabsence of oxygen, produce a black oil which has a strong sulfur andamine odor. Although the oil has an appearance much like crude oil, itscomposition is substantially different.

While both crude oil and pyrolysis oil contain pentane (C5), heptane(C7) and other alkane insolubles, the insolubles from crude oil consistof paraffins and asphaltenes. Insolubles from pyrolysis oil consist ofpolar compounds such as benzoic acid and oxygenates, sulfur and nitrogencompounds.

Tire pyrolysis oil has currently been used as a crude fuel or for downwell application in order to clear oil well deposits. It has been knownto collect fractions of the oil by distillation, but except for thefractions at the very light ends, the distillates are black and containan objectionable sulfury/amine odor. It has been suggested that theblack color was entrained carbon, however, when filtration was attemptedin order to remove the black color, this was not successful.

In spite of the known prior art, there remains a very real andsubstantial need for solutions to the foregoing problems.

SUMMARY OF THE INVENTION

The method and apparatus of the present invention effectively reducesthe undesired black color to a transparent dark amber and preferably toa transparent yellow which is more preferred with light transparentyellow being most preferred. The invention also effects a meaningfulreduction in the undesired sulfury/amine odor. Finally, the preferredfinal product will have a reduction in the level of PAH's and be under 1ppm of the PAH Benzo(a)pyrene.

The temperature range for removal of solvent from oil or clay residue isfrom the boiling point of the solvent up to about the boiling point ofthe oil fraction. For example, for hexane, when being used to processthe unfractionated pyrolysis oil, the temperature range would be about68° C. to 100° C. It has been found that exceeding the upper limitincurs an increase in the cost of the process without providing anoffsetting comparable benefit. A preferred temperature range would bebetween 68° C. and 78° C. and the most preferred temperature range wouldbe between 68° C. and 70° C.

In alternate embodiments of the invention, separation may be effected bya distillation column or a wiped film evaporator (WFE) with a jacket orheater heating the hexane, solvent and oil mixture to above thesolvent's boiling point but not above the boiling point of the oil.Another advantage of the embodiments employing the distillation tower orwiped film evaporator is subject to the capacity of the column andevaporator, the operation may be performed on a continuous basis limitedonly by the capacity of the clay column.

It is an object of the present invention to provide a method andapparatus for efficiently clarifying pyrolysis oils.

It is a further object of the invention to provide an efficient andeconomical means for accomplishing such clarification.

It is yet another object of the invention to produce the desiredtransparent yellow color for the processed pyrolysis oil.

It is another object of the present invention to produce pyrolysis oilwhich does not have the objectionable sulfury/amine odor.

It is yet another object of the present invention to reduce the amountof PAH present in the processed oil.

It is yet another object of the present invention to provide a desirablelight yellow color for the pyrolysis oil while eliminating the undesiredsulfury/amine odor and reducing the PAHs in order to enhance thecommercial value of the processed pyrolysis oil.

It is another object of the present invention to provide a system forseparating pyrolysis oil from a solvent which is mixed therewithemploying a distillation column wherein heating is effected above theboiling point of the solvent.

It is yet another object of the present invention to provide a systemfor separating a solvent which is admixed with pyrolysis oil employing awiped-film evaporator.

In a further embodiment, it is another object of the present inventionto provide a method and apparatus for continuous operation subject tothe limits imposed by the capacity of column absorbent packing.

It is another object of the present invention to provide alternateembodiments which employ either a distillation column or a wiped filmevaporator in effecting separation of the nonpolar solvent from thepyrolysis oil.

These and other objects of the invention will be readily apparent fromthe following detailed description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a form of apparatus employable inthe present invention using a distillation-elution method.

FIG. 2 is a schematic illustration of a form of apparatus employable inthe present invention employing a forced flow-elution method.

FIG. 3 is a schematic illustration of another embodiment of thedistillation elution apparatus of the present invention employing awiped film evaporator (WFE).

FIG. 4 is a schematic illustration of another embodiment of thedistillation-elution apparatus employing a packed column employable inthe method of the present invention.

FIG. 5 is a plot of weight percent versus temperature versus derivativeweight percent showing the relationships in drying clay.

FIGS. 6 through 10 are schematic views showing the operation of subunitsof the general system shown.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides methods and apparatus for removing thepolar compounds. Removal is accomplished by adjustment of conditionssuch that the polar compounds bind to activated attapulgite which isalso known as palygorskite. We have tried a number of other materialswithout meaningful success. These included but were not limited tobentonite, montmorillonite, activated carbon, charcoal, carbon black anddiatomaceous earth, but were not successful in producing the desiredresult.

The invention also contemplates methods and apparatus for regeneratingthe clay with a polar solvent and then reactivating the same.Reactivation may be accomplished using the same apparatus and methods asfor elution, but with the said polar solvent.

The method of the present invention involves initially adjusting thepolarity of the unfractionated pyrolysis oil or pyrolysis oil fractions,absorption of the contaminants onto clay followed by elution andseparation of the clean oil from the adjusting solvent.

The polarity may be adjusted by dilution with a nonpolar solvent whichmay be an alkane or combination of several alkanes. The alkanes may beones having 4 to 10 carbons (butane, pentane, hexane, heptane, octane,nonane or decane) and preferably pentane, hexane, and heptane (C5-C7)with hexane (C6) being the preferred alkane. If desired, combinations oftwo or more alkanes may be employed in the method.

The unwanted components are absorbed onto the attapulgite. Theseunwanted components include alkane-insolubles of polar compounds such asbenzoic acid, quinolone, steric acid oxygenates, sulfur-containingcompounds and nitrogen-containing compounds. The methods and apparatusof the present invention removes the polar compounds. This may beaccomplished by precipitation and filtration or centrifugation ofinsolubles and binding of the polar compounds to activated attapulgiteclay. The removal of the polar compound not only removes the black colorand undesired odor, but the pyrolysis oil maintains its physical andchemical properties. This is followed by elution of the clean oil in thenonpolar solvent. The solvent is then separated from the oil byevaporation. After that, the column is cleaned for reuse with a polarsolvent such as acetone, methanol, tetrahydrofuran or dimethylformamideor other polar solvents, for example.

The heavier end of pyrolysis oil is known to contain variouspoly-aromatic hydrocarbons (PAHs) including benzo(a)pyrene which is themost carcinogenic of this compound group. It has been found that thepresent invention clarifies the oil color, reduces the odor, and hasreduced levels of PAHs.

The method of the present invention involves removal, by precipitationand adsorption of the black material from the oil by using an alkane oralkane mixture selected from the group consisting of C4 through C10(butane, pentane, hexane, heptane, octane, nonane and decane). Thepreferred alkane is one selected from the group consisting of alkanes C5through C7 (pentane, hexane and heptane). The most preferred alkane ishexane.

The oil to be charged onto the column is diluted with an alkane solventat a ratio of about 1:2 to 1:30 (oil to alkane) by volume and,preferably, of about 1:4 to 1:15 and, most preferably, of about 1:6 to1:10. The diluted oil is aged by sitting at room temperature for atleast 30 minutes to allow precipitation. The aged diluted oil can befiltered or centrifuged to remove precipitate prior to charging onto thecolumn or it can be charged onto the column without removingprecipitate. The oil is charged slowly onto the top of the bed and thefluid is collected from the bottom of the column. For example, thiscould involve approximately 0.22 liters per hour of column flow perliter of void volume (using a column with approximately 18.2-liter voidvolume is equivalent to 4 liters per hour column flow). The range offlow rates is about 0.1 to 0.6 liters per hour of column flow per literof void volume, a preferred range would be about 0.2 to 0.4 liters perhour of column flow per liter of void volume and a most preferred rangewould be about 0.3 to 3.5 liters per hour of column flow per liter ofvoid volume.

The ratio of clay to oil to be clarified is in the range of about 4:1 to20:1 by weight, or preferably about 6:1 to 15:1 by weight and, mostpreferably, about 6:1 to 10:1 by weight. The greater weight enhancesrecovery.

FIG. 1 illustrates an alternate method (referred to herein as“distillation-elution method”) of processing the pyrolysis oil whichmethod is slightly preferred over the forced-flow-elution method to bedescribed herein in connection with FIG. 2. One advantage over theforced-flow-elution method is that the distillation-elution method usesless solvent and, therefore, can be more advantageously employedeconomically.

While both the methods and apparatus of FIGS. 1 and 2 will effectivelypractice the present invention, there is a preference for FIG. 1. Thedistillation-elution method and apparatus (shown in FIG. 1) employs lesssolvent to elute material from the column in the elution phase andemploys less wash solvent in the wash phase, Also, since the column iseluted and washed with distilled solvent, it typically operates at ahigher temperature than the forced-flow-elution method. This results ineluting and washing at greater efficiencies.

With respect to eluting oil, there are two effective alternateprocedures for washing the column. In an example of the first method,hexane is delivered to the top of the bed by means, for example, of apump and is allowed to migrate down by gravity. The flow is controlledthrough the columns at approximately 4 liters per hour washing the bedwith up to 30 bed volumes using a valve at the bottom of the column. Theeluent contains extracted oil and hexane. The oil and hexane iscollected in a vessel and separated from each other by distillation at atemperature sufficient to evaporate hexane (68° C.), but not high enoughto evaporate the oil. The recovered oil is recovered at the distillationcolumn bottom. The column is then washed and prepared for the next cycleof operation.

In an example of the second elution process, freshly distilled hexane isdelivered to the top of the column using a distillation system where theeluent bottom of the column is heated at a temperature sufficient toevaporate hexane (68° C.), but not high enough to evaporate the oil.

The evaporation temperatures for a particular solvent being employed forelution or cleaning and for a particular pyrolysis oil fraction are (1)between the boiling point of the particular solvent and 32° C. above theboiling point of the most volatile compound in the particular pyrolysisoil fraction or (2) preferably, between the boiling point of theparticular solvent and 10° C. above the boiling point of the mostvolatile compound in the oil fraction or (3) most preferably, betweenthe boiling point of the particular solvent and 2° C. above the boilingpoint of the most volatile compound in the oil fraction.

For example, for hexane being used to clarify unfractionated pyrolysisoil, the ranges would be (1) between about 68° C. to 100° C. or (2)preferably between about 68° C. and 78° C. or (3) most preferably,between about 68° C. and 70° C. The ranges for the other alkanes will beknown to those skilled in the art and can be readily determined.

While the preferred alkanes are ones having 4 to 10 carbons, it will beappreciated that they may be employed individually, in the process,hexane and butane, for example, may be employed in combinations. Also,while for purposes of example, hexane, the preferred alkane has beenused individually, other alkanes within the preferred group having 4 to10 carbons may be employed individually.

In this manner, solvent is delivered to the top of the columncontinuously. The flow is controlled through the column at approximately4 liters per hour, washing the bed with up to 30 bed volumes using valveat the bottom of the column.

The difference between this process and a known standard columnchromatography process is our distillation-elution method employed lesssolvent and higher temperature. The present invention differs fromsoxhlet which is used to continuously soak a solid, in our case clay, toremove bound or captured material. It does not flow the solvent throughthe material in a top down fashion as is required for chromatography,thus, it is not appropriate for our process. In another process, fiberthimbles permit the residue to flow out to the sides of the crucible.This brings a portion of the extract to the bottom of the vessel withoutresidence time with clay thereby minimizing contact therebetween.

Our process has been found to be more effective for removal of the polarsubstances from the oil and polar substances from the column duringcleanup.

An example of a cycle of operation of the system of FIG. 1 will beconsidered. The system shown in FIG. 1 employs evaporation and gravityin order to deliver solutions and uses about 10 to 15 times less solventthan the forced-flow elution method shown in FIG. 2 to be describedhereinafter. In order to achieve the same degree of purification in thisexample of the distillation-elution method, the oil and hexane are mixedat an oil to hexane ratio of about 1.4 to 1.15 and most preferably about1:6 to 1:10 ratio of oil to hexane prior to charging onto the column.The oil and hexane are mixed in vessel 13 and is allowed to sit forabout two or more hours. Solids that precipitate in vessel 13 may beremoved by filtration or centrifugation or can be left suspended in thisfluid. The liquid is fed by gravity through valve 24 to column 17 atapproximately the rate of 0.22 liters per hour of column flow per literof void volume. The bottom valve 26 remains closed for about 1 to 2hours contact time. Valve 26 is opened and a volume of hexane equivalentto the oil and hexane mix in tank 20 is maintained at a boilingtemperature by heat exchanger 14 which is at least 68° C. for hexane.The hexane vapors travel through tube 16 and are condensed by condenser10. The condensed hexane drips through valve 24 and on to and throughcolumn 17 and then from valve 26 into tank 20. The flow is preferablycontrolled at about 0.1 to 0.6 liters per hour of column flow per literof void volume using valve 26. The oil elution process is complete afterabout 10 to 30 column bed volumes of hexane have been eluted throughcolumn 17.

At this point valve 23 is opened and valve 24 and 26 are closed. Thecontents of tank 20 are heated to at least 68° C. to remove the hexanecompletely by evaporation from tank 20. In the case of hexane, it isevaporated from tank 20, passes through tube 16 through open valve 23and is condensed by condensers 10 and 12 for delivery to tank 18.Product oil in tank 20 is then drained through valve 25 into tank 21.After that, valve 25 is closed and tank 21 is replaced with a cleantank. The residual hexane is removed from the clay by closing valves 24and 26 to isolate the column 17 and heating the column using heatexchanger 15 to evaporate residual hexane through condenser 11 and intotank 18.

The column is then cleaned with a polar solvent. The preferred solventfor cleaning the clay is acetone. In the case of acetone, it istransferred into tank 20 while valves 23, 25 and 26 are in the closedposition. Valve 24 is open to the condenser 10. Tank 20 is heated to theboiling point of acetone using exchanger 14. The acetone from tank 20evaporates and passes through tube 16, after which it is condensed incondenser 10 and drips through valve 24 and onto and through column 17.The bottom valve 26 is open to allow dripping into tank 20. This iscontinued for about 30 bed volumes (the volume of clay in the column isa “bed volume”). Tanks 18 and 21 are replaced with clean tanks for thispart of the process. Valves 24 and 26 are closed and valve 23 is open.Tank 20 continues to be heated until the acetone is completelyevaporated. The acetone vapors travel through tube 16 and are condensedthrough condensers 10 and 12. Recovered acetone is collected in tank 18.The waste material collected in tank 20 is drained through valve 25 intotank 21 for disposal or alternate use. The tanks are then cleaned andare ready for their initial set up for the processing of the next batch.

FIG. 2 illustrates schematically an example of a forced-elutionapparatus usable in the method of the present invention. In thisexample, a ratio of oil to hexane of 1:6 to 1:10 is employed. Theoil-hexane mixture is in vessel 40 and is allowed to sit for about twohours. Solids that precipitate in the vessel 40 may be removed by eitherfiltration or centrifugation or can be left suspended in this fluid. Theliquid is pumped through valve 33 by pump 31 and onto column 22. The oilis pumped slowly onto the top of the bed and fluid is collected from thebottom of the column 22 at approximately 0.22 liters per hour of columnflow per liter of void volume (using a column with approximately an 18.2liters void volume which is equivalent to 4 liter per hour column flow).Once the material is charged onto the column 22, the column bottom valve36 is closed for about 1 to 2 hours to allow sufficient contact timebetween the liquid and the clay. Valve 36 is then opened and valve 33 isturned open to allow hexane from tank 41 to be pumped by means of pump31 onto the column 22 at a rate of approximately 0.22 liters per hour ofcolumn flow per liter of void volume (using a column with approximatelyan 18.2 liter void volume which is equivalent to 4 liters per hourcolumn flow.) The column is then washed with about 30 times the volumeof oil-hexane that was charged into the column of hexane from tank 41with valve 36 open, 37 closed and valve 35 in the open position and intotank 27. Tank 27 is heated to approximately 68° C. by heating jacket 28and vapors condensed by condenser 44. Hexane is collected in tank 45until only oil remains in tank 27. The cleaned oil is then deliveredthough valve 37 into tank 29. Valves 33, 35, 36, 37 are closed withvalve 32 being open. Jacket 42 is heated and jacket 43 is cooled toallow the residual hexane to be removed from the column 22 and the clayto be dried. Tank 45 will hold all recovered hexane which ultimatelywill be pumped through valve 38 by pump 30 to tank 41 for reuse.

The evaporation temperatures for a particular solvent being employed forelution or cleaning and for a particular pyrolysis oil fraction is (1)between the boiling point of the particular solvent and 32° C. above theboiling point of the most volatile compound in the particular pyrolysisoil fraction or (2) preferably, between the boiling point of theparticular solvent and 10° C. above the boiling point of the mostvolatile compound in the oil fraction or (3) most preferably, betweenthe boiling point of the particular solvent and 2° C. above the boilingpoint of the most volatile compound in the oil fraction.

For example, for hexane being used to clarify unfractionated pyrolysisoil, the ranges would be (1) between 68° C. to 100° C. or (2) preferablybetween 68° C. and 78° C. or (3) most preferably, between 68° C. and 70°C.

A column bed that could treat four liters of oil employed in an exampletest was approximately 18 inches in diameter and 24 inches high and havea capacity of approximately 34 liters. The bed was filled with about 16Kg of clay which is approximately 32 liters and was wet withapproximately 20 liters of hexane. The column distribution consisted ofscreen plates and glass wool at the top and at the bottom with a valveat the bottom to control flow.

As shown in FIG. 2, valve 38 is opened and the contents of tank 45 ispumped through pump 30 into tank 41. When the transfer is complete,valve 38 is closed. Tank 41 is replaced with a tank containing acetone.Acetone from tank 41 is pumped though valve 33 using pump 31 and isdelivered into column 22. The acetone extracts the material in column 22and delivers it through open valve 36 into tank 27.

The material collected in tank 27 is evaporated to collect acetone intotank 45. Vapors passing through open valve 35 are condensed by coolingjacket 44 with the acetone being collected until only waste residueremains in tank 27. The temperature ranges for the wash procedure are asdescribed hereinbefore. Waste material from tank 27 is drained throughvalve 37 to tank 29 for disposal or alternate use. The tanks are thenreplenished to the initial setup conditions for the next cycle ofoperation.

The following discloses two alternate embodiments with respect to theforegoing disclosure which focus on separation of vaporized nonpolarsolvents and separating them from the pyrolysis oil using in oneinstance a wiped film evaporator and, in another, distillation column.Apart from the specific way disclosed method and apparatus variationsfocusing on these alternate embodiments the preferred characteristicsmay remain the same as the foregoing.

The additional embodiments disclosed in this continuation-in-partapplication involve the use of a wiped film evaporator (WFE) or adistillation column. The solvent is stripped from the oil exiting theclay column using a distillation column or a wiped-film evaporator(WFE). This involves heating the mixture of oil and solvent in a tank ata temperature above the solvent's boiling point and below the boilingpoint of the oil.

The variations in the system for clarification of pyrolysis oil shown inFIGS. 3 and 4 employ evaporation and gravity in order to deliversolutions to the column as does the original invention. Identicalreference numbers will be employed for the same elements in both FIGS. 3and 4. These embodiments also use about 10 to 15 times less solvent thanthe forced-flow elution method shown in FIG. 2 of the originalapplication. In addition, these embodiments allow for continuousoperation, limited to the capacity of the absorbent packing column 69.In order to achieve the same degree of purification in this example ofthe distillation-elution method, the oil and alkane, which is preferablyhexane, are mixed at a ratio of oil to alkane of about 1:4 to 1:15, andpreferably a 1:6 to 1:10 ratio of oil to hexane prior to charging ontothe absorbent column 69. The oil and hexane are mixed in vessel 63 andthe mixture is allowed to sit for at least about two hours. Solids thatprecipitate in vessel 63 may be removed by filtration or centrifugationor can be left suspended in this fluid. The liquid is fed by gravitythrough valve 74 to absorbent packing column 69 at approximately therate of about 0.1 to 0.6 liters per hour of column flow per liter ofvoid volume and preferably, at a rate of about 0.2 to 0.3 liters perhour of column flow per liter void volume. The bottom valve 76 remainsclosed for about 1 to 2 hours contact time. Heat exchanger 65 may beemployed to heat the oil and hexane mixture in absorbent packing column69 to vaporize the hexane. Valve 76 is opened to a position to allowhexane and eluted oil to flow through pipeline 80 to heated distillationcolumn 67 where the hexane is stripped from the oil and the oil isdelivered by gravity through valve 77 to tank 70. The hexane invaporized form is stripped from the oil and flows through wiped filmevaporator 66 (WFE) or distillation column 67 is condensed by condenser60 (FIG. 3) or 82 (FIG. 4), respectively and drips through valve 74 onto and through absorbent packed column 69 (FIG. 3). The flow continuesthrough absorbent packed column 69 through valve 76 and back into wipedfilm evaporator 66 (FIG. 3) or distillation column 67 (FIG. 4). The flowcontinues through absorbent column 69 and out of the bottom throughvalve 76 and through pipeline 80 and onto WFE 66 or absorbent packedcolumn 67 where the cycle continues. The flow is preferably controlledat about 0.1 to 0.6 liters per hour of column flow per liter of voidvolume using valve 76 and temperature control in Wiped Film Evaporator66 or column 67. The oil elution process is complete after about 10 to30 column bed volumes of hexane have been eluted through absorbentpacked column 69 or WFE 67 or the absorbent column effluent isclarified.

Tank 63 is allowed to empty and absorbent packed column 69 is drainedthrough pipe 80. Then valve 74 is positioned to stop flow from tank 63and valve 73 is opened to allow flow through condenser 60 by pipeline63, 77 and into hexane receiving tank 68. Tank 63 is allowed to emptyand absorbent packed column 69 is drained through column 66 to completethe cycle. Recovered vaporized hexane passes by pipeline 78 throughcondenser 61 and is collected in tank 68. At this point, the packing inabsorbent packed column 69 is regenerated. After the process has beencompleted, the clay may be regenerated by washing with a polar solvent.

Regeneration is preferably accomplished in the following manner. Valve73 is opened and valves 74 and 76 are closed. Product oil in tank 70 isthen drained through valve 75 into tank 71. After that, valve 75 isclosed and tanks 68 and 71 are replaced with clean tanks. Absorbentpacked column 69 is then cleaned with a polar solvent. The preferredsolvent is acetone. The polar solvent is transferred into tank 63 whilevalve 74 is in the closed position. Valves 74 and 76 are opened andacetone flows through absorbent packed column 69, through valve 76, andinto WFE 66 (FIG. 3) or column 67 (FIG. 4). Acetone strips residue oilfrom absorbent packed column 69 and flows out of the top of column 66and through absorbent packed column 69 and continues the cycle. Theresidue from absorbent packed column 69 and WFE 66 transfers by gravityto tank 70. This is continued for about 20 to 40 bed volumes (the volumeof clay in the column is a bed volume) or until column 69 effluent isclear. Valve 74 is positioned to close tank 63 and open pipeline 76. Theacetone is drained from absorbent packed column 69 and cycled throughcondenser 82 which condenses vaporized hexane which passes through theabsorbent packed column 66 through valve 76 and pipeline 80 to WipedFilm Evaporator 66 or column 67 through condenser 60, 82, respectivelyinto tank 68. Heat exchanger 65 is heated to between about 150° C. and250° C., valve 74 is closed and residual acetone is driven from thewiped film evaporator 66 or column 67 and flows in pipeline 78 and iscondensed through condenser 61 into tank 68 for reuse. The wastematerial collected in tank 70 is drained through valve 75 into tank 71for disposal or alternate use. The tanks are then cleaned and are readyfor their initial set up for the processing of the next batch.

Referring to FIG. 4, it will be appreciated that the major components ofthe system and mode of operation are generally similar to that of thedistillation column embodiment of FIG. 3. In this embodiment, a column67 is employed. The mixture of vaporized hexane and oil passes throughvalve 76 and pipeline 80 to the wiped film evaporator 67. The portionexiting from the top is condensed in condenser 82 and is either recycledto absorbent packed column 69 or passes through valve 74 to absorbentpacked column 69 and then through pipe 78 passes through condenser 61and is delivered to tank 68. The lower portion of column 67 has itsseparated oil delivered through valve 77 to tank 70. The operation ofthis embodiment is otherwise similar to the embodiment of FIG. 3. Theoil in tank 70 can be heated by means of heat exchanger 64 if it isnoted that hexane is observed to condense in the tank.

We have found that the attapulgite clay works more efficiently afterbeing activated. Activation may be accomplished by drying it at about120° C. to 300° C. and preferably about 140° C. to 250° C. until thereis no weight change. Referring to FIG. 5, the appropriate temperaturewas reached using a TGA with a ramp rate of 10° C./minute to 700° C.Although the clay can be dried above 150° C., clay tends to decompose atthat temperature and loses much of its capacity. FIG. 3 shows theresults of Thermogravimetric Analysis (TGA) of the attapulgite testingshowing the percent weight loss as a function of temperature. Thisprofile shows the temperature at which free water and hydrated watersevolve. We have found that driving off the higher temperature hydrationwaters decreases capacity of the clay for the clarification residues.

In cleaning the clay for reuse, it is preferred to use a polar solventsuch as selected from the group consisting of acetone, methanol,tetrahydrofuran, dimethyl-formamide or another solvent suitable for thepurpose. At present, acetone is the preferred polar solvent for thispurpose. In cleaning, the flow is controlled through the column atapproximately 4 liters per hour washing the bed with up to 30 bedvolumes using the valve at the bottom of the column.

In another embodiment, freshly distilled hexane is continuouslydelivered to the top of the column using a distillation system whereinthe eluent from the bottom of the column is heated to a temperaturesufficient to evaporate the polar solvent, but not high enough toevaporate the oil. For example, for hexane, an effective range might beabout 68° C. to 75° C. The ranges for other alkanes known to thoseskilled in the art can readily be determined. In this manner, freshsolvent is delivered to the top of the column continuously. The flow iscontrolled through the column at about 2 to 8 liters per hour, with apreferred rate of about 3 to 5 liters per hour washing the bed with upto about 30 bed volumes using a valve at the bottom of the column.

Referring generally to FIG. 6, it is seen that the hexane feed 200 andpyrolysis oil feed 202 are mixed at 204. The mixture of the pyrolysisoil and the nonpolar solvent which preferably may be hexane, isdelivered to filtration unit 206 resulting in a solubles filtrate 208and insolubles filter residue 210. After filtration to remove undesiredmaterials in the filtration unit 206, the oil/hexane output offiltration unit 206 is directed through solubles 208 clay bed 212. Theoutput of insolubles 210 will be combined with residual oil 214. Oilfrom the clay bed 212, also known as the absorbent packed column, willbecome the feed for a distillation unit in FIG. 7.

Referring now to FIG. 7, there is shown a subunit of the globalschematic for stripping hexane from the clay bed eluent and separatingthe hexane from the oil. This is achieved by the distillation unit 302.Hexane 300 is evaporated and condensed 304 and fed to the top of theclay bed 212 and flows through carrying cleaned oil to the distillationunit 302 to continue the cycle. The heavier clarified oil 306 isseparated by gravity and is collected.

Referring to FIG. 8, which shows another subunit of the global processof FIG. 6 in which residual hexane 300 is driven off of the clay bed 212through the condenser 301 and collected for reuse. The clay bed 212 isheated to above the boiling point of hexane but, below the boiling pointof the process oil.

Referring to FIG. 9, the clay bed is cleaned with a polar solvent,preferably acetone 400 to remove the polar residue oil 214. Acetone 400strips residue oil 214 from the clay column 212. The distillation unit302 strips the acetone 400 from the residue oil 214/acetone 400 elutedfrom the clay bed 212. The residue oil 214 drains down and the acetone400 evaporates and is condensed and cycled back to the clay bed 212.This results in the clay bed having been cleaned.

Referring to FIG. 10, the residual acetone 400 from the clay bed 212 isremoved by heating and condensing 304. This is similar to the processcomponent described in FIG. 8. The clay bed 212 is heated to above theboiling point of acetone, but not above the boiling point of the residueoil.

While the schematics of FIGS. 6 through 10 have shown the distillationunit, the alternate embodiment would at the same position, use the wipedfilm reactor in the manner disclosed herein.

Whereas particular embodiments of the invention have been described forpurposes of illustration, it will be evident to those skilled in the artthat numerous variations of the details of the present invention may bemade departing from the invention as defined in the appended claims.

What is claimed is:
 1. A method of processing pyrolysis oil comprisingadjusting the polarity of unfractionated pyrolysis oil with a nonpolarsolvent causing precipitation of insoluble components, effectingseparation of insoluble components from said pyrolysis oil, binding saidinsoluble components to clay, combining said pyrolysis oil with saidnonpolar solvent, and separating the nonpolar solvent from the pyrolysisoil employing a method selected from the group consisting of adistillation column and a wiped film evaporator.
 2. The method of claim1 including effecting said separation of said nonpolar solvent from saidpyrolysis oil by a distillation column.
 3. The method of claim 1including effecting said separation of a said nonpolar solvent from saidpyrolysis oil by a wiped film evaporator.
 4. The method of claim 1including employing an alkane as said nonpolar solvent.
 5. The method ofclaim 4 including employing as said an alkane selected from the groupconsisting of alkanes having 4 to 10 carbons.
 6. The method of claim 4including employing as said an alkane selected from the group consistingof alkanes having 5 to 7 carbons.
 7. The method of claim 4 includingemploying a mixture of two or more alkanes selected from the groupconsisting of alkanes having 4 to 10 carbons.
 8. The method of claim 1including removing said insoluble components from said clay, andemploying hexane as said nonpolar solvent.
 9. The method of claim 4including mixing said pyrolysis oil and alkane to adjust polarity. 10.The method of claim 4 including mixing said pyrolysis oil and alkanepreferably in a ratio of oil to alkane to about 1:4 to 1:15.
 11. Themethod of claim 8 including mixing said pyrolysis oil and alkane in aratio of pyrolysis oil to alkane to about 1:6 to 1:10.
 12. The method ofclaim 9 including heating said mixture of oil and alkane to volatilizesaid alkane.
 13. The method of claim 12 including separating saidvolatilized alkane from said pyrolysis oil.
 14. The method of claim 12including condensing said volatilized alkane.
 15. The method of claim 12including effecting said heating to at least the boiling point of saidalkane.
 16. The method of claim 12 including effecting said heating ofsaid alkane to between the boiling point of said alkane to about 10° C.above the boiling point of the most volatile component of said pyrolysisoil.
 17. The method of claim 1 including employing attapulgite as saidclay.
 18. The method of claim 1 including prior to initiating a cycle ofsaid method activating said clay.
 19. The method of claim 17 includingthe ratio of said clay to said pyrolysis oil being about 4:1 to 20:1 byweight.
 20. The method of claim 17 including cleaning said clay torecover said insoluble components.
 21. The method of claim 20 includingemploying a polar solvent to effect said cleaning of said clay.
 22. Themethod of claim 21 including employing acetone as said polar solvent.23. The method of claim 21 including employing as said polar solvent amaterial selected from the group consisting of methanol, tetrahydrofuranand dimethylformamide.
 24. The method of claim 2 including creating flowof said oil-alkane mixture through said column at the rate of about 0.1to 0.6 liters per hour of column flow per liter of column void volume.25. The method of claim 14 including separating said condensedvolatilized alkane from said pyrolysis oil.
 26. The method of claim 12including employing hexane as said alkane.
 27. A method of processingpyrolysis oil comprising adjusting the polarity of unfractionatedpyrolysis oil with a nonpolar solvent causing precipitation of insolublecomponents, effecting separation of insoluble components from saidpyrolysis oil, binding said insoluble components to clay, combining saidpyrolysis oil with said nonpolar solvent, separating the nonpolarsolvent from the pyrolysis oil employing a method selected from thegroup consisting of a distillation column and a wiped film evaporator,employing an alkane as said nonpolar solvent, and after mixing saidpyrolysis oil and alkane, allow the mixture to sit for at least 2 hoursto allow precipitation of said insoluble components.
 28. A method ofprocessing pyrolysis oil comprising adjusting the polarity ofunfractionated pyrolysis oil with a nonpolar solvent causingprecipitation of insoluble components, effecting separation of insolublecomponents from said pyrolysis oil, binding said insoluble components toclay, combining said pyrolysis oil with said nonpolar solvent,separating the nonpolar solvent from the pyrolysis oil employing amethod selected from the group consisting of a distillation column and awiped film evaporator, removing said insoluble components from saidclay, cleaning said clay to recover said insoluble components, employingattapulgite as said clay, and employing a distillation column inrecovering said insoluble components bound to said clay.
 29. A method ofprocessing pyrolysis oil comprising adjusting the polarity ofunfractionated pyrolysis oil with a nonpolar solvent causingprecipitation of insoluble components, effecting separation of insolublecomponents from said pyrolysis oil, binding said insoluble components toclay, combining said pyrolysis oil with said nonpolar solvent,separating the nonpolar solvent from the pyrolysis oil employing amethod selected from the group consisting of a distillation column and awiped film evaporator, removing said insoluble components from saidclay, employing a wiped film evaporator in recovering said insolublecomponents bound to said clay.
 30. Apparatus for processing pyrolysisoils comprising a first vessel for receiving a mixture of said pyrolysisoil and a nonpolar solvent, a heater for volatilizing said nonpolarsolvent in said first vessel, employing apparatus selected from thegroup consisting of a distillation column and a wiped film evaporator ineffecting separation of said volatilized nonpolar solvent from saidpyrolysis oil, a first condenser for receiving said volatilized nonpolarsolvent and condensing the same, and a clay column for receivingcondensed vapors from said first condenser and eluting said nonpolarsolvent therefrom.
 31. The apparatus of claim 30 including employing adistillation column in effecting said separation.
 32. The apparatus ofclaim 30 including employing a wiped film evaporator in effecting saidseparation.
 33. The apparatus of claim 31 including said distillationcolumn structured to deliver said volitalized nonpolar solvent to saidfirst condenser and oil separated by said distillation column to asecond vessel.
 34. The apparatus of claim 32 including said wiped filmevaporator structured to deliver said volatilized nonpolar solvent tosaid first condenser and oil separated by said wiped film evaporator toa second vessel.
 35. The apparatus of claim 30 including said apparatusstructured to process nonpolar solvents which are alkanes having 4 to 10carbons.
 36. The apparatus of claim 30 including said apparatusstructured to process a nonpolar solvent which is hexane.
 37. Theapparatus of claim 33 including said second vessel structured to receivesubstantially all of said pyrolysis oil and no substantial nonpolarsolvent.
 38. The apparatus of claim 34 including said second vesselstructured to receive substantially all of said pyrolysis oil and nosubstantial nonpolar solvent.
 39. The apparatus of claim 30 includingsaid apparatus structured to employ a polar solvent to clean said claycolumn after a cycle of operation.
 40. The apparatus of claim 39including said apparatus structured to employ acetone as said claycleaning polar solvent.
 41. The apparatus of claim 30 including saidapparatus being structured to be employed in both the processing of saidmixture of pyrolysis oil and nonpolar solvent and the cleaning of saidapparatus after a cycle of operation.
 42. An apparatus for processingpyrolysis oils comprising a first vessel structured to receive a mixtureof said pyrolysis oil and a nonpolar solvent, a clay column operativelyassociated with said first vessel for receiving said mixture, said claycolumn structured to heat said mixture to a temperature at which saidnonpolar solvent will vaporize, said apparatus having a unit selectedfrom the group consisting of a distillation column and a wiped filmevaporator for separating said vaporized nonpolar solvent from saidpyrolysis oil, a condenser for condensing said vaporized nonpolarsolvent, a second vessel for receipt of said condensed vapors, and athird vessel for receiving oil separated from said mixture of saidpyrolysis oil and vaporized nonpolar solvent.
 43. The apparatus of claim42 including said unit being a distillation column, and said apparatusstructured to process nonpolar solvents which are alkanes having 4 to 10carbons.
 44. The apparatus of claim 42 including said unit being a wipedfilm evaporator said apparatus structured to process nonpolar solventswhich are alkanes having 4 to 10 carbons.
 45. The apparatus of claim 42including said apparatus structured to process a plurality of differentnonpolar solvents which are alkanes having 4 to 10 carbonssimultaneously.
 46. The apparatus of claim 44 including delivery meansfor delivering a clay cleaning polar solvent to said clay column after acycle of operation.
 47. The apparatus of claim 44 including saidapparatus structured to process a nonpolar solvent which is hexane. 48.The apparatus of claim 46 including said clay cleaning polar solventbeing acetone.
 49. The apparatus of claim 46 including said clay beingattapulgite.
 50. The apparatus of claim 49 including said apparatusstructured to activate said clay before performing a next cycle of saidprocess.
 51. The apparatus of claim 50 including said apparatusstructured to effect said activation by drying said clay at up to about150° C. until there is no significant additional weight loss.